The present application has been filed with claiming priority based on Japanese Patent Application No. 2002-23263, filed on Jan. 31, 2002. Disclosure of the above-identified Japanese Patent Application is herein incorporated by reference.
1. Field of the Invention
The present invention relates generally to a laminated heating body, such as a disposable warmer or the like. More particularly, the invention relates to a laminated heating body having a cover sheet covering a heating body and including a portion having heat conductivity different from that of remaining portion.
2. Description of the Related Art
A warmer, such as a disposable warmer, is a laminate body of a heating body and a cover sheet wrapping the heating body. The cover sheet is typically formed into a bag shape for achieving a function for sealingly enclosing the heating body received therein and a function for transmitting heat generated from the heating body to a user""s skin. In case of the conventional disposable warmer, the cover sheet is formed from non-woven fabric or the like.
On the other hand, in Japanese Unexamined Patent Publication No. Heisei 4 (1992)-300542, a disposable warmer is disclosed, in which a heat conducting medium is disposed between the heating body and the cover sheet covering the former.
The disposable warmer disclosed in the above-identified publication has the heating body disposed between an upper non-woven fabric and a lower non-woven fabric. A film form heatconducting medium is disposed between the heating body and the lower non-woven fabric. Area of the film form heat conducting medium is wider than area of the heating body.
In the disposable warmer disclosed in the above-identified publication, heat generated by the heating body can be transmitted to wider area by means of the film form heat conducting medium to widen heat source. Also, a thickness of the body of the disposable warmer can be reduced.
However, conventionally, the disposable warmer, in which the heating body is covered with the non-woven fabric, encounters shortcoming in low heat transmission efficiency to transmit heat generated by the heating body to the skin of the user.
On the other hand, in the disposable warmer disclosed in the above-identified publication, while it can widen range to transmit the heat generated by the heating body, since widely distributed heat is transmitted to the skin of the user through the non-woven fabric, heat transmission efficiency to the user""s skin is still low to be unsatisfactory for providing warm feeling for the skin of the user over wide range.
The present invention has been worked out in view of the shortcoming in the prior art set forth above. It is therefore an object of the present invention to provide a laminated heating body, in which heat conductivity from a heating body to a user""s skin is improved to provide satisfactorily warm feeling to the skin of the user.
According to one aspect of the present invention, a laminated heating body comprises:
a heating body; and
a cover sheet covering the heating body, the cover sheet defining at least one low temperature portion formed from a material having low heat conductivity and at least one high temperature portion formed from a material having high heat conductivity, the at least one low temperature portion and the at least one high temperature portion being formed separately on a surface of the cover sheet contacting with a user""s skin.
In the laminated heating body according to the present invention, heat generated by the heating body is efficiently transmitted to the user""s skin through the high temperature portion formed of a material having high heat conductivity. Since the cover sheet maintains temperature difference between the high temperature portion and the low temperature portion, excessive heat should not be applied to the user""s skin. Thus, appropriately high and comfortable temperature can be applied to the user""s skin. Also, since heat can be easily transmitted to the user""s skin from the high temperature portion, the user may feel as if skin is warmed in wide area.
For example, the cover sheet may be consisted of a sheet base and a heat conductive member fitted on a plurality of portions of the sheet base and having higher heat conductivity than the sheet base, the sheet base forms the low temperature portion and the heat conductive member forms the high temperature portion. The heat conductive member may be at least one of a metal plate or a metal foil. The cover sheet may also be consisted of a sheet base and at least one kind of metal plate or metal foil fitted on a plurality of portions of the sheet base, the sheet base forms the low temperature portion and each of the metal plate or the metal foil forms at least one kind of the high temperature portion.
The metal plates or metal foils fitted on various portions on the sheet base can be formed of the same metal. In the alternative, the metal plates or metal foils to be fitted on various portions on the sheet base can be formed of different metals. By forming the metal plates or metal foils of different metals, temperatures at respective high temperature portions can be differentiated. In this case, different portions of the user""s skin are warmed at mutually different temperatures. This may give the user to be warmed uniformly in wide area.
For example, the sheet base may be formed from a non-woven fabric or a woven fabric.
On the other hand, in the cover sheet, the sheet base is placed in opposition to the heating body, and the metal plate or the metal foil is located on a surface of the sheet base remote from the heating body. The metal plate or the metal foil may be directly opposing to the heating body. The sheet base may be formed with openings, and the metal plates or the metal foils may be arranged at portions of the openings.
As set forth above, the metal plate or the metal foil may be arranged on the surface of the sheet base remote from the heating body, or in the alternative, in direct contact with the heating body depending upon high and low of the heat conductivity. Depending upon nature of the heating body or heat conductivity of the metal plate or metal foil, heat transmission to the user""s skin can be optimized.